Problem: Simplify the following expression: ${-7+9(9z-4)}$
Solution: Distribute the ${9}$ into the parentheses: $ -7 + {9(}\gray{9z-4}{)} $ $ -7 + {81z-36} $ Rewrite the expression to group the numeric terms: $ 81z {-7 - 36}$ Combine the numeric terms: $ 81z {-43}$ The simplified expression is $81z-43$